Description
6
SNOU165A – September 2018 – Revised March 2019
Copyright © 2018–2019, Texas Instruments Incorporated
Using the LMG341xEVM-018 half-bridge and LMG34XX-BB-EVM breakout
board EVM
2.1.3
Bootstrap Mode
The LMG341xEVM-018 card can be modified to operate in bootstrap mode, where the 12V bias voltage is
used to power both LMG341xR050 devices. This can be achieved by removing U3, U4 and R2, and
placing a 20
Ω
resistor on R1, a 0
Ω
resistor on R18 and a 600V SOD-123 diode on D1, such as Micro
Commercial Components UFM15PL-TP. Do NOT power up the LMG341xEVM-018 when R1, R2, R7, D1,
U4 and U5 are all populated.
2.1.4
Heatsink
Heatsink is installed to help with heat dissipation of the LMG341xR050. Exposed copper pads that are
attached to the die attach pad (DAP) of both the high and low side devices are provided for a low thermal
impedance point to a heatsink. The two copper pads have high voltage potential difference between them
so an electrically isolative thermal interface material (TIM) is required. Please refer to
for the
recommended TIM and mechanical fixture.
Figure 2. Top Side View of LMG341xEVM-018
Figure 3. Back Side View of LMG341xEVM-018
2.2
LMG34XX-BB-EVM
To allow for quick operation the LMG34XX-BB-EVM is available to interface with the LMG341xEVM-018.
This mother board is designed to operate the LMG341xR050 as a synchronous open loop buck converter.
Easy probe locations are provided for measurement of logic and power stage voltages.
2.2.1
Bias Supply
The motherboard requires one 12V bias supply. A linear drop off regulator steps the voltage down to a
tightly regulated 5V for logic and auxiliary power of the LMG341xR050 when the LMG341xEVM-018 is
configured in isolated power mode. When the LMG341xEVM-018 is configured in bootstrap mode the 12V
input is used to power the two LMG341xR050 devices.
2.2.2
Logic PWM Input
The LMG34XX-BB-EVM supports a single PWM, with complimentary signal and corresponding dead time
generated on board. A 0 V to 5 V magnitude input square wave is required. The complementary PWM
generation circuit creates 50 ns of dead time between both transitions of the PWM signals.
